Cases for holding compact discs are well known to the art. Such cases can made of molded polystyrene, impact (rubber-doped) styrene, polyethylene or polypropylene. These cases are an inexpensive packaging which are used to store and display the discs for sale. Even though the case is relatively inexpensive, when compared to the cost of the compact discs it holds, it must be strong enough to hold the discs over a long period of time and withstand frequent opening, closing, dropping and rough handling during shipping and processing on an automated assembly line. Industry requirements and consumer preferences have dictated the dimensions of the case. Sizes greater than these dimensions, especially greater thicknesses, have led to a lack of acceptance by the retailers because oversized cases take up more shelf space and by the consumers because they are more difficult to store, especially by those who own large numbers of compact discs.
The recording, software, game and movie industries currently market works which are so lengthy they require more than one compact disc. Increasing the thickness of the case to accommodate a second disc is not always acceptable to the consumer. The industry has sought a case for two compact discs which has the same thickness as a case for the single compact disc and is compatible with automated packaging equipment currently in use.
Popular cases currently available for storing compact discs include a rectangular base, a corresponding rectangular cover pivotally connected to the base and a rectangular tray for holding the compact disc fixedly connected to the base. The rectangular tray includes a receiving surface for the disc and a circularly-shaped, radially-disposed array of spring fingers which receive the center hole of the compact disc and hold it there by an interference fit.
The United States Patent to Lammerant et al., U.S. Pat. No. 5,244,085, and the United States Patent to Dunker, U.S. Pat. No. 5,284,248, disclose a modification of existing compact disc cases which enables the storage of two compact discs in a case previously adapted to hold only one compact disc. To provide for holding two compact discs, a tray which heretofore had been fixedly held within the base of the case was pivotally mounted in the base so access to the tray can be gained from either side of it. The compact discs are held by a tenon system including teeth which stand around an opening formed in the tray. Half of the teeth stand facing the cover and the other half stand facing the base. One set of teeth holds one compact disc and the other set holds another compact disc on the opposite side of the tray. The individual teeth are supported by a ring disposed within the opening in the tray. The ring is suspended from the opening by a radial arrangement of spokes. Such spokes are relatively weak and cannot always support the weight of the compact discs. Dropping a case will frequently break or shear the spokes or the teeth and render the tray inoperative. In addition, small differences in diameters of the center holes of the compact discs (in the order of 0.1 to 0.2 mm) can also break the spokes and teeth during automatic assembly operations which place discs on trays at rates up to 80 discs per minute.
To provide additional strength to the trays and the spokes, the composition of the trays was modified by doping it with a rubber to make the components more resilient. Doping allows the teeth to move laterally without breaking as easily. But doping the styrene with rubber causes the tray to become opaque and adopt the color of the dopant which makes the appearance less desirable.
Literature providing sales and identification materials is conventionally disposed within the case against the cover, the base and the spine. Information stored beneath the tray cannot be seen through an opaque tray. Because the package allows limited area for art work and information, a transparent tray can increase the value of the case by adding another viewing surface. But since the styrene is extremely rigid and because the teeth which hold the compact discs are easily broken, it has not been acceptable, heretofore, to provide unitarily-molded trays without adding opacity producing materials.
Attempts have been made to rigidify the fingers of transparent trays holding the compact discs thereby to provide more support. Exemplary is a tray disclosed in the United States Patent to Joyce et al., U.S. Pat. No. 5,417,324. In the patent, two ribs are used to tie together four opposing spring fingers. While such tied-together fingers reduced finger breakage, they were unsuitable for holding two compact discs. Moreover, they reduce the amount of resilience provided by the fingers and, because of their rigidity, they cannot accommodate holes in compact discs of different diameters. The Gartz patent, U.S. Pat. No. 5,558,220, discloses a rigid central hub for holding two compact discs as an integral part of a transparent tray. While extremely sturdy, users of the tray were limited in their ability to remove compact discs since they could be removed from one direction only because of locking lips which hold the compact discs in place on the tray.